I've found a great online tool for formatting c# code for blogs.  It's available here.  You cut and paste the code you want to post into the page and select a few options, press generate, and the output is ready for you to put into your blog.  You can see an example of this in my previous post (and future ones I'm sure).

The one small caveat is that you need to add a stylesheet for the coloring / formatting, and since I use BlogEngine.NET I needed to add the css file to the server and modify the default master page in my current theme.  No big problem, but something you have to do.